Retrozetes

Colloff, Matthew J., 2012, New eremaeozetid mites (Acari: Oribatida: Eremaeozetoidea) from the south-western Pacific region and the taxonomic status of the Eremaeozetidae and Idiozetidae, Zootaxa 3435, pp. 1-39 : 19

Retrozetes gen nov.

Diagnosis. Cerotegument thick, reticulate-alveolate. Lamellae extremely long, elevated above prodorsum; separated and recurved apically, extending well beyond rostrum and prominent projecting tutorium; with narrow slit or broad separation anteriorly. Lamellar setae on medial margins of lamellar cusps, sub-apical. Lamellar cuspides folded ventrally in the transverse plane. Interlamellar setae present. Bothridial seta with long stalk, broadening and barbed apically. Bothridium small, cup-shaped. Dorsosejugal suture transverse; bounded laterally by conical apophyses of setae c 2 positioned on strongly reduced dorsosejugal lobes. Lenticulus strongly protuberant on conical projection, positioned close to dorsosejugal suture. Notogaster in dorsal view broader than long; in lateral view wedge-shaped with posterior margin elevated; centrodorsal region convex, elevated. Notogaster with ten pairs of setae, lm in centrodorsal position; at least one pair of sacculi. Mentum elongated, anterior margin not reflexed. Epimeral setal formulae 2-1-2-2 or 2-1-2-1. Pre-genital sclerite absent. Genital and anal plates separated by distance of about half length of genital setae. Aggenital setae present. Six pairs of genital setae, all in alignment, g 1 not displaced laterally of others. Anal setae two pairs, with or without thick, bacilliform cerotegument. Setae ad 2- 3 positioned close together near lateral margin of ventral plate; ad 1 in post-anal position. Legs monodactylous. Solenidion σ on genu I greatly elongated, flagelliform.

Type species. Retrozetes koghisensis sp. nov.

Remarks. Retrozetes shares character states with Idiozetes including the presence of sacculi; the very long lamellar cuspides; the conical, protuberant lenticulus; a strongly projecting tutorial apex, the enclosed bothridia with small openings and a rim without an incision and the long, typically thin, blade-like pteromorphs. Retrozetes also shares character states with Rogerzetes, particularly the sub-apical lamellar setae; the lamellar cuspides folded ventrally in the transverse plane; the transverse dorsosejugal suture and with setae lm close together in the centrodorsal position.

Eremaeozetes hanswursti Mahunka 1999 from Singapore is a Retrozetes based on the following character states and is hereby recombined: 1) in lateral view the notogaster is wedge-shaped and deepest posteriorly and the circumgastric scissure is clearly visible; 2) the centrodosal region with an oval area; 3) the humeral region and cerotegument of humeral regions strongly triangular (cf. Fig. 12 of Mahunka, 1999 and Fig. 15 herein); 3) the marginal arrangement of the notogastral setae except the centrodorsal lm and the presence of a saccule medial to seta lp; 4) the genital setae are aligned longitudinally: g 1 is not displaced laterally as in Eremaeozetes ; 5) the configuration of the lamellae with a central, expanded notch and medially-opposed lamellar setae in dorsal view and reflexed (though covered in cerotegument) in lateral view; 6) the large anal setae each at the far ends of the plate, curved and covered in thick cerotegument; 7) its small size, 152-158 μm long, fits closer with the length of Retrozetes spp. (mean 308 μm, range 252–356 μm) than Eremaeozetes spp. (mean 426 μm range 288–614 μm).

Figures

FIGURE 12. Retrozetes koghisensis sp. nov., a) left palp, antiaxial view; b) anal plates with cerotegument removed showing anal setae; c) ovipositor.

FIGURE 15. Retrozetes novaecaledoniae sp. nov., holotype female; a) dorsal, with cerotegument; b) dorsal, with cerotegument removed.